Ribonuclease solution behavior

The initial decrease in optical rotation found in aqueous solutions of /3-lactoglobulin and ovalbumin is not, however, sufficient to differentiate globular proteins from simpler synthetic polypeptides in their transition behavior, for neither ribonuclease nor human serum albumin appear to exhibit it. The specific rotation of ribonuclease in water-2-chloroethanol mixtures becomes steadily less levorotatory as the proportion of nonpolar solvent increases (Weber and Tanford, 1959). In the case of human serum albumin Bresler (1958) and Bresler el al. (1959) find that only progre.ssive increases in specific rotation occur as the concentration of 2-chloroethanol is increased and that this change is accompanied by a steady rise in viscosity and the corresponding axial ratios characteristic of the formation of rodlike particles. If these proteins do have some initial helical content in water, as can be argued from their optical rotatory dispersion, then it appears that hydrophobic forces are not required for the stability of these regions. 

Heat affects the conformation of proteins, and most proteins undergo fairly rapid heat denaturation somewhere between 333 and 363 A series of experiments was made by Roscoe and Fuller in which the surface adsorption behavior of bovine )8-lactoglobulin A, hen egg-white lysozyme and bovine pancreatic ribonuclease A was studied at a platinum electrode as a function of temperature using cyclic voltammetry. The protein solution and the electrochemical cell were separately immersed in the thermostated bath and allowed to equilibrate for 30 mins. The protein... 

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